Fortran subroutine attid1

subroutine input and utput parameters:

x(1..12),z(1..2) - attitude coefficients data set for the given time
      interval corresponding to a line in attitude coefficients arrays;

ts  - time in thousands of sec relative to beginning of the interval
      (negative values supported) (input);

u1,u2  - direction in the S/C frame, degrees (input)
         u1 - angle between vector and X axis (polar angle)
         u2 - angle on the YZ plane from Y axis (anticlockwise);

dir(1..2..3) - corresponding unit vector in the GSE frame (output)


      subroutine attid1(ts,u1,u2,dir)
      common /z/ z(2)
      common /c/ x(12)
      dimension s(3),e(3),p2(3),dir(3),dra(3),pa(3,3)
      ux=atan(1.)/45.*u1
      uy=atan(1.)/45.*u2
      dra(1)=cos(ux)
      dra(2)=sin(ux)*cos(uy)
      dra(3)=sin(ux)*sin(uy)
      alf=x(1)+x(2)*sin(x(11)*ts)+x(3)*cos(x(11)*ts)+x(4)*sin(x(12)*ts)+
     *x(5)*cos(x(12)*ts)
      bet=x(6)+x(7)*sin(x(11)*ts)+x(8)*cos(x(11)*ts)+x(9)*sin(x(12)*ts)+
     *x(10)*cos(x(12)*ts)
      rgr =   atan(1.)/45
      al =alf*rgr
      tga=tan(al )
      be =bet*rgr
      tgb=tan(be )
      s(1)=1./sqrt(1.+tga**2+tgb**2)
      s(2)=     tga *s(1)
      s(3)= tgb     *s(1)
      g=z(1)+z(2)*ts
      ax=s(2)*cos(g)+s(3)*sin(g)
      e(1)=-ax/sqrt(ax**2+s(1)**2)
      e(2)=sqrt(1.-e(1)**2)*cos(g)
      e(3)=sqrt(1.-e(1)**2)*sin(g)
      call vect (e,s,p2)
          do 1 i=1,3
          pa(1,i)=  s(i)
          pa(2,i)= p2(i)
    1     pa(3,i)=  e(i)
      do 2 i=1,3
    2 dir(i)=0
      do 3 i=1,3
      do 3 j=1,3
    3 dir(i)=dir(i)+pa(i,j)*dra(j)
      return
      end
      subroutine vect(x,y,z)
      dimension x(3),y(3),z(3)
      z(1)=x(2)*y(3)-y(2)*x(3)
      z(2)=x(3)*y(1)-x(1)*y(3)
      z(3)=x(1)*y(2)-x(2)*y(1)
      zz=sqrt(z(1)**2+z(2)**2+z(3)**2)
      do 1 i=1,3
    1 z(i)=z(i)/zz
      return
      end